In stereotaxic neurosurgery, a headring is secured to a patient's skull, a localizing unit is affixed to the headring, and then, utilizing medical imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), digital substraction venous angiography (DSVA) or positron emission tomographical scanning (PET), a target point for the lesion in the brain is established. The headring, which is immobilized in relation to the patient's head, thereafter serves as the base for attaching what is known as an arc system, and it is in relation to the arc system that the possible entry points, angular settings, and distances to the target point are computed. Following selection of the entry point, an appropriate instrument, such as a biopsy instrument, is supported by the arc system for carrying out the selected medical procedure.
Therefore, a key to all such procedures is fixing the headring in a selected position to the upper portion of a patient's skull (calvarium). In the past, that has usually been carried out while a patient is under general anesthetic even though there could be substantial advantages in performing such a step while the patient is awake. (Brain tissue has no nerve sensors and local anesthetics would eliminate pain associated with forming the small surgical entry opening or attaching the headring to the patient's skull.) If no general anesthetics were required, the risks and costs of such an operation would be reduced, no hospitalization would be necessary and the entire procedure, which generally takes less than one hour, might be performed on an outpatient basis. However, a main problem with performing such a procedure while a patient is awake is that patients requiring neurosurgery may be, partly by reason of their affliction, uncooperative, confused, or obtunded. Discomfort, or fear of discomfort, may also be involved. Such factors may result in head movements that could make it difficult, if not impossible, for a surgical team to anchor a stereotaxic headring in a precise position on a patient's head while the patient remains awake.
Prior efforts to stabilize a headring have involved the use of Velcro-type straps (as in the Brown-Roberts-Wells (BRW) stereotaxic system) or bars inserted into the auditory meatus (as in the Leksell system), but neither arrangement insures against relative movement between a ring and patient's head or does anything to immobilize the head itself. Therefore, general anesthetics have still been considered necessary.
Accordingly, one aspect of this invention lies in recognizing that the aforementioned problems could be overcome, and a stereotaxic headring could be applied even while a patient is awake, if, first, a patient's head were immobilized or fixed against movement relative to the shoulders and upper torso, and second, a stereotaxic headring were then adjusted and fixed in relation to the same rigid brace used to immobilize the head. Since both the head and headring would be fixed in relation to the patient's shoulders and torso, they would be fixed in relation to each other.
Once a patient's head is so immobilized and a stereotaxic headring is supported by the brace in its selected position of adjustment, local anesthetics may be applied at the entry or attachment points and nylon screws may be used in the usual manner to secure the headring to the patient's calvarium. Thereafter, the brace may be removed, leaving the headring fixed to the patient's head for use as stereotaxic neurological procedures require.
Briefly, the bracing means for the stereotaxic headring takes the form of a rigid body plate, preferably in the form of a chest plate, having a pair of shoulder rests that extend over a patient's shoulders. Straps are secured to the shoulder rests and plate for immobilizing the plate with respect to a patient's shoulders and upper torso. A plurality of support members in the form of rigid bars are adjustably mounted on the body plate, and clamps are adjustably fixed to the support members for supporting a stereotaxic headring at circumferentially-spaced points. A chin support is adjustably secured to the body plate, and a rear head support is also adjustably anchored to the body plate for contacting the occipital area and posteriorly bracing the head. The head support and chin support, in combination with the body plate, immobilize the head in relation to the upper torso, and the support members and clamps anchor the stereotaxic headring against movement with respect to the brace and, hence, with respect to the patient's head.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.